Clang: Don't reparse if the macros haven't changed

We have to extend that to include paths too, which will be happen in a
follow up patch.

Change-Id: I7f8ac663ae8588e647fc6a6b5d689a629a28ef65
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/tools/clangrefactoringbackend/source/clangrefactoringbackend-source.pri

@@ -18,6 +18,7 @@ HEADERS += \
     $$PWD/usedmacro.h \
     $$PWD/sourcedependency.h \
     $$PWD/filestatus.h \
+    $$PWD/projectpartartefactexception.h \
     $$PWD/projectpartartefact.h
 
 !isEmpty(LIBTOOLING_LIBS) {